Multicell battery having membrane sealed between cover and container

ABSTRACT

A membrane extends between and is sealed to the mating exterior and interior surfaces of the container and cover of a multicell battery to provide a liquid-tight seal across the top of each cell compartment inside the battery. The space above the membrane in each of the cell compartments may be used as an electrolyte storage compartment in a battery having dry, charged electrodes. With or without the spaces above the membrane being used to store electrolyte in each cell compartment, the membrane may be used to seal and thus maintain the factory dryness of dry, charged electrodes. As another alternative, the membrane can be used with a &#39;&#39;&#39;&#39;wet&#39;&#39;&#39;&#39; battery (one having electrolyte in contact with the electrodes when shipped from the factory) to prevent spilling or leaking of electrolyte during battery shipment or storage.

United States Patent 1 Consolloy 51 Jan. 30, 1973 [75] Inventor: JamesW. Consolloy, Pennington,

[73] Assignee: ESB Incorporated [221 Filed: June 29,1971

[21] Appl. N0.: 157,847

Related U.S. Application Data [63] Continuation of Ser. No. 885,856,Dec. 17, 1969,

3,376,166 4/1968 Hruden ..136/l14' 3,480,480 11/1969 Merz et a1..;....l36/l13 3,485,678 12/1969 Blaich et al ..l36/l70 PrimaryExaminerWinston A. Douglas Assistant Examiner-C. F. LeFevourAtt0rneyRaymond L. Balfour, Robert H. Robinson and Anthony J. Rossi [5717 ABSTRACT A membrane extends between and is sealed to the matingexterior and interior surfaces of the container and cover of a multicellbattery to provide a liquidtight seal across the top of each cellcompartment inside the battery. The space above the membrane in each ofthe cell compartments may be used as an electrolyte storage compartmentin a battery having dry, charged electrodes. With or without the spacesabove the membrane being used to store electrolyte in each cellcompartment, the membrane may be used'to seal and thus maintain thefactory dryness of dry, charged electrodes. As another alternative, themembrane can be used with a wet battery (one having electrolyte incontact with the electrodes when shipped from the factory) to preventspilling or leaking of electrolyte during battery shipment or storage.

8 Claims, 6 Drawing Figures SHEETIUF 2 PATENTED JAN 30 I975 PATENTEDJAH30 1973 SHEET 2 BF 2 MULTICELL BATTERY HAVING MEMBRANE SEALED BETWEENCOVER AND CONTAINER CROSS-REFERENCE TO PRIOR APPLICATION Thisapplication is a continuation of Ser. No. 885,856, filed Dec. 17, 1969now abandoned.

BACKGROUND OF THE INVENTION There is a need for an automotive batterywhich can be either activated by the addition of water alone orpreferably be activated without the addition of anything from a sourceexternal to the battery. To achieve this requires the storage inside thebattery of electrolyte or some substance which will produce theelectrolyte in the presence of water,

One means for storing electrolyte inside the battery has been to build areservoir into the cover; see U.S. Pat. No. 2,832,814. Another has beento place an electrolyte capsule inside the container and above theelectrodes; see for example US. Pat. Nos. 2,733,927, 3,304,202, and3,455,740, which differ from each other in the means by which thecapsules are opened. Each of these prior constructions has had arelatively high cost and the walls of the reservoirs or capsules haveoccupied a significant portion of the volume inside the battery.

' There is also a need for a means to maintain the factory dryness ofthe charged automotive battery.

There is also a need for a means to prevent theelectrolyte of a wetbattery (one having electrolyte in contact with the electrodes whenshipped from the factory) to prevent spilling or'leaking of electrolyteduring battery shipment or storage.

SUMMARY OF THE INVENTION With this invention a membrane is placedbetweenand sealed to the exterior and interior walls of both the container andcover to provide a liquid-tight seal across the top of each cellcompartment. The space above the membrane in each of the cellcompartments may be used as an electrolyte storage compartment in abattery having dry, charged electrodes. With or without the spaces abovethe membrane being used to store electrolyte in each cell compartment,the membrane may be used to seal and thus maintain the factory drynessof dry, charged electrodes in each cell compartment. As anotheralternative, the membrane can be used with a wet" battery to preventspilling or leaking of electrolyte during battery shipment or storage.

Preferably the cover and the container are made from thermoplasticmaterials and the membrane is heat sealed to and between the containerand the cover.

The membrane may be shaped to have a contour matching that of each cellcompartment above the electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of a sixcell battery showing a container, a cover, and a membrane between thecontainer and cover. Terminals are shown extending to the exterior ofthe container.

FIG. 2 is a-sectional view taken along the line 2-2 of FIG. 1. FIG. 2shows the membrane between the container and cover, the membrane beingsealed to both the container and the cover. The dashed line representsan alternative configuration and position for the membrane. A vent wellis shown as part of and projecting downward from the upper surface ofthe cover.

FIG. 3 is similar to FIG. 2 except that a terminal is shown projectingupward to extend through the cover.

FIG. 4 is similar to FIG. 2 except that the vent well projects downwardfarther and is sealed to the mem- DESCRIPTION OF THE PREFERREDEMBODIMENTS FIG. I shows a container 10 having exterior and interiorwalls 12 and 14, respectively, whichdivide its interior space into aplurality of cell compartments 16. In each cell compartment arealternately spaced positive and negative electrodes between which areseparators, these being collectively identified by the numeral 18. Thepositive electrodes in one cell compartment are mechanically andelectrically connected together by positive strap connectors 20 whilethe negative electrodes in that same cell compartment are similarlyconnected together by negative strap connectors 22. The positive strapconnector in one cell compartment is electrically connected to thenegative strap connector in an adjacent cell compartment by anyconvenient means. The two strap connectors 20 and 22 may initially beseparate pieces which are'subsequently electrically connected togetherat some point in the battery assembly process, or they may be the twoends of a single piece intercell strap connector which extends throughthe partition 14 either in a lot in the partition or as an insert aroundwhich the partition is molded.

FIG. 1 shows terminal means 24 extendingto the exthe battery to theexterior of the container. The terminals may be of any desiredconfiguration and may be constructed in any desired manner, includingbeing extensions of the strap connectors in the two end cellcompartments around which extensions the exterior walls of the containerare molded. I

Also shown in FIG. 1 is a cover 26 for the container, the cover having avent well 27 for each cell compartment. The cover has exterior andinterior walls 28 and 29, respectively, on the underside thereof. In theasse'mbled battery the exterior and interior walls of the cover matewith and are sealed to the respective exterior and interior walls of thecontainer to provide liquid tight cell compartments.

Between the container 10 and the cover 26 is a thin membrane 30, shownin FIG. 1'. It is the purposeof this invention to seal the membrane tothe mating exterior and interior walls of both the cover and containerto provide a liquid-tight seal across the top of each cell compartmentinside the battery.

In each of the constructions shown in FIGS. 2 through 6 the membranecould be used either to maintain the dryness of the electrodes in a dry,charged battery or to prevent the spilling of leaking of electrolytefrom beneath the membrane in a wet battery. The remainder of thediscussion will focus on another possible function of the membrane, thatof a component of an electrolyte storage compartment which permitsstorage of electrolyte above the membrane in each cell compartment.

FIGS. 2 through 6 illustrate several of many possible batteryconstructions which may use the membrane to provide an internalelectrolyte storage compartment. Each illustration shows the commonfeature of the membrane between the container and the cover, themembrane being sealed to the exterior and interior walls of both thecontainer and the cover. Among the considerationsin battery designillustrated by FIGS. 2 through 6 are'the ability to get the electrolyteinto the storage compartment after the container, cover, and membraneare sealed together; the ability to keep electrolyte from spilling outof the storage compartment before the membrane is opened; the ability toadd water to the cell compartments beneath the storage compartmentsbefore the membrane is opened to release the electrolyte; and theability of gases generated by the battery when in u'seto be exhausted tothe exterior of the battery.

FIG. 2 is a cross section showing the cover 26 and membrane 30 afterthey have been sealed to the container 10. The vent well 27- in thecover has a pair of slots 34 which have been conventionally provided invent wells for the purpose of permitting gases generated by the batteryto escape rather than be trapped below the upper surface of the cover.In addition to serving this conventional function after batteryactivation, the slots '34 .will also permit the escape of air from theelectrolyte storage compartment while the electrolyte is being added. Toprevent escape of electrolyte, from the storage compartment beforeactivation a vent plug may .be' fitted into the vent well 'or some smallmembrane may be sealed across the top of the vent well; neither the ventplug nor the small membrane appears in FIG. 2. Note in FIG. 2 that thereis no opportunity for water to be added to the cell compartment 16'before the membrane 30 is opened to release the stored electrolyte; thisconstruction maybe used where the concentration of the electrolytestored in the compartment 32 is such that it will not damage theseparators below without. first being diluted. Water could be added tothe battery after the membrane '30 is opened. if desired.

FIG. 3 is similar to FIG. 2 except-that a terminal cor responding infunction to the oneidentified by the numeral 24 ,in' FIG. 1 is shownprojecting upward to extend through the cover. Like the constructionsshown in FIG.2, the terminal extendsto the exteriors of the coveredcontainer. Because of the identity of function the terminal shown inFIG. 3 is also identified bythe numeral 24. The terminal must project-upthrough the membrane 30and, toprevent leakage of the electrolyte betweenthe membrane and the terminal, there should be a seal between the two.FIG. 3 shows a construction which easily permits a heat seal. In FIG. 3a portion 36 of the cover projects downward and surrounds the terminalwhile a portion 38 of the container projects upward and also surroundsthe terminal; the membrane 30 is sealed between the two portions, themating surfaces of which may be heated prior to scaling.

FIG. 4 is similar to FIG. 2 except that the vent well 27 projectsdownward farther so that its bottom may be sealed to the membrane 30,and a portion 40 of the membrane having a closure 42 across its top andresembling a finger projects upward into the vent well. With thisconstructionelectrolyte could be introduced into the storage compartment32 through the slots 34 by being poured into the vent around the portion40 of the membrane. When it is desired to activate the battery theclosure .42 of the portion 40 may first be opened and water then pouredthrough the portion 40 into the cell compartment 16; afterward theupstanding walls of the portion 40 may be punctured to allow theelectrolyte to flow into the cell compartment.

FIG. 5 also has a vent well 27 projecting downward and being sealed tothe membrane 30, similar in this respect to the construction shown inFIG. 4. The cover 10 shown in FIG. 5 also is provided with a second hole44 which may be provided for the purpose of introducing electrolyte intothe storage compartment. The hole 44 may be relatively large if desired,and covered with some kind of seal or plug to prevent the electrolytefrom spilling out prior to battery activation. Alternately, the hole 44may be relatively small as shown in FIG. 5, small enough so that theelectrolyte could beintroduced by a hypodermic needle, which-needlecould also remove air from the storage compartment while the electrolytewas being added and thus make slots 34 in the vent well unnecessary orless'necessary; after addition of the electrolyte the small hole 44could be simply left open as a subsequent venting device or couldbeclosed by being heat sealedshut, by being filled with cement by beingplugged with some frictionfitting device, etc. If the hole 44 is closedafter-addition that if the vent well 27 is sealed to the membrane 30 theportion of the membrane 30 inside the vent well may first be puncturedso that water may be 'added to the cell compartment 16 after which ahook-like puncturing device may be used to puncture the membrane outsideof the vent well and release the stored electrolyte.

FIG. 6 is similar to FIG. 2 except that the vent well projects downwardfarther and has a lower-section of reduced diameter. As in FIG. 5, theven well- 27 is sealed to the membrane. The vent well also has slots 34.With the, construction shown in FIG. 6 water could lower section; afterthe puncturing device was inserted into the vent well but before it isremoved it could be used as a filling tube through which water could bepoured into the cell compartments. The slots 34, which of these otherconfigurations and positions is the membrane shown by the dashed line inFIG. 2. The membrane may be shaped to match the contour of the cellcompartment above the electrodes and separators, both to provide maximumsize in the storage compartment 32 and to receive vertical support fromthe electrodes and separators. Shaping of the membrane to match thecontour of the cell compartment may be done after the membrane is placedacross the top of the cell compartment by using thermoformingtechniques. The membrane shown in the drawings is shown flat for sake ofsimplicity, for ease in illustrating the concept, but the invention isnot limited to such a simple configuration.

The battery shown in the drawings differs from the one illustrated inU.S. Pat. No. 2,832,814 by providing a much larger electrolyte storagecompartment as well as being easier and less expensive to construct. Theincreased size of storage compartment results from the fact that thethickness of the membrane may be quite small (forinstance, from 0.005 to0.020 inch might be typical). In addition to permitting a greater volumeof electrolyte to be stored, the increased size makes it possible tostore electrolyte of lower concentration, an advantage because itreduces the threat of damage by concentrated electrolyte to theseparators and points to a battery construction in which theconcentration of the stored electrolyte is that which is required in thebattery after its activation, that is to say the battery might beactivated without the addition of either-concentrated electrolyte orwater from an external source.

The membrane also permits an easy and inexpensive construction of anelectrolyte storage compartment, particularly where the container,cover, and membrane are made from thermoplastic materials and are heatsealed together. In the absence of a membrane the mating surfaces ofsuch coversand containers are first heated and' then pressed togetherwhile still hot to achieve the sealing. The simplicity of using themembrane can be seen from the fact that the membrane may be placedbetween the container and cover just before they are pressed together,so that the act of sealing the container and cover to the membrane maybe done by utilizing a step which would have to be performed even in theabsence of the membrane rather than by a new and additional step. Themembrane may be placed between the cover and containerin the same motionin which the heating element which heated their mating surfaces isremoved. An additional advantage of the use of heat as a sealingtechnique is that the heat dissipates quickly and the desired seal maybe achieved quickly, whereas if some other techniques such as cementing18 used a greater time delay may be involved before further processingafter the sealing step. The membrane is preferably heated before beingsealed to the cover and container. While the use of thermoplasticmaterials such as polypropylene or polyethylene and the use of heat as asealing technique are preferred, the invention may also be used withother materials and sealing techniques. While the membrane is shown ashaving the same length and width dimensions as the container, it may ifdesired be larger during battery assembly with the excess being removedafter the cover and container are sealed together. i

I claim:

1. A multicell battery comprising the combination of:

a. A container having exterior and interior walls which divide the spaceinside the container into a plurality of cell compartments;

b. a cover having exterior and interior walls on the underside thereof,the exterior and interior walls of the cover mating with and sealed tothe respective exterior and interior walls of the container;

0. positive and negative electrodes within the container; and,

. terminal means for conducting electrical current between the exteriorof the covered container and the positive electrodes and additionalterminal means for conducting electrical current between the exterior ofthe covered container and the negative electrodes;

wherein the improvement comprises a membrane between the cover andcontainer, the membrane being sealed to the exterior and interiorwallsof both the container and cover to provide a liquidtight seal across thetop of each cell compartment.

2. The battery of claim 1 in which the cover and the container are madefrom thermoplastic materials and the membrane is heat sealed to thecontainer and the cover.

3. The battery of claim 1 in which the membrane is sealed around theterminal means extending upward through the cover. I

4. The battery of claim 1 in which the membrane is sealed to a vent wellprojecting downward from the inner surface of the cover. .1

5. The battery of claim 1 in which the membrane is sealed around theterminal means extendingupward through the cover and in which themembrane is also sealed to a vent well projecting downward from theinner surface of the cover.

6. The battery of claim 2 in which the membrane is heat sealed aroundthe terminal means extending upward through the cover.

7. The battery of claim 2 in which the membrane is heat sealed to a ventwell projecting downward from the inner'surface of the cover.

8. The battery of claim 2 in which the membrane is heat sealed aroundthe terminal means extending upwardthrough the cover and in which themembrane is heat sealed to vent'well projecting downward from the innersurface of the cover.

1. A multicell battery comprising the combination of: a. A containerhaving exterior and interior walls which divide the space inside thecontainer into a plurality of cell compartments; b. a cover havingexterior and interior walls on the underside thereof, the exterior andinterior walls of the cover mating with and sealed to the respectiveexterior and interior walls of the container; c. positive and negativeelectrodes within the container; and, d. terminal means for conductingelectrical current between the exterior of the covered container and thepositive electrodes and additional terminal means for conductingelectrical current between the exterior of the covered container and thenegative electrodes; wherein the improvement comprises a membranebetween the cover and container, the membrane being sealed to theexterior and interior walls of both the container and cover to provide aliquid-tight seal across the top of each cell compartment.
 1. Amulticell battery comprising the combination of: a. A container havingexterior and interior walls which divide the space inside the containerinto a plurality of cell compartments; b. a cover having exterior andinterior walls on the underside thereof, the exterior and interior wallsof the cover mating with and sealed to the respective exterior andinterior walls of the container; c. positive and negative electrodeswithin the container; and, d. terminal means for conducting electricalcurrent between the exterior of the covered container and the positiveelectrodes and additional terminal means for conducting electricalcurrent between the exterior of the covered container and the negativeelectrodes; wherein the improvement comprises a membrane between thecover and container, the membrane being sealed to the exterior andinterior walls of both the container and cover to provide a liquid-tightseal across the top of each cell compartment.
 2. The battery of claim 1in which the cover and the container are made from thermoplasticmaterials and the membrane is heat sealed to the container and thecover.
 3. The battEry of claim 1 in which the membrane is sealed aroundthe terminal means extending upward through the cover.
 4. The battery ofclaim 1 in which the membrane is sealed to a vent well projectingdownward from the inner surface of the cover.
 5. The battery of claim 1in which the membrane is sealed around the terminal means extendingupward through the cover and in which the membrane is also sealed to avent well projecting downward from the inner surface of the cover. 6.The battery of claim 2 in which the membrane is heat sealed around theterminal means extending upward through the cover.
 7. The battery ofclaim 2 in which the membrane is heat sealed to a vent well projectingdownward from the inner surface of the cover.